1. Field of the Invention
The present invention relates to a position detecting circuit for use in an apparatus performing position control for example an original reading apparatus.
2. Description of the Prior Art
FIG. 1 is a drawing for showing principle of detection performed in a prior art example of a position detecting system. Referring to the figure, reference numeral 18 denotes a light emitting device, 19 denotes a rotating member, 20 denotes a slit made in the rotating member, 21 denotes a photosensor device, and 22 denotes a counter.
Below will be described operation of the above mentioned arrangement. Light emitted from the light emitting device 18 is introduced through the slits 19 made in the rotating member 20 into the photosensor device 21 and thereby converted into an electric signal. The electric signal becoming a pulse signal is counted in number of pulses by the counter 22 and thereby the position of the rotating member is detected.
The detecting method in the prior art position control system has been of the type to pick up a signal carrying information about position and it therefore has had a mechanical arrangement in the detecting portion. Consequently, there have been such problems that the system requires complex and large size structure and its detecting accuracy is low.